Propeller



Patented Oct. 18, 1927.

UNITED STATES HUGO urinarias, or nEssAU, GERMANY.

PROPLLER.

Application `tiled July 1, 1925, Serial No. 40,780, and 'in Germany lTuly 17, 1924.

My invention refers to propeilers more especially for use in connection with flying machines. It is an object of my invention to provide ,a propeller, the blades of Awhich are attached'to the hub in a more reliable manner than was the case in the propellers hitherto used.

n In propellers, the blade of which is fixed to the hub by its shaft, the points where the blades are attached to the hub are subject to strains which vary both in magnitude and in direction. These strains are the cause of vibrations of the blade shafts relative to the hub body,`which can even lead to a breakage. 'Inv propellers, in which the blade shaft-s are connected with sleeves on the hub by screwing, the centrifugal forces beingtaken up by the screw thread, lone has tried to provide for the vibrating stresses by pressing the end of the hub sleeve against the shaft of the blade. However, such pressing together of the parts in a single place can never be entirely successful and oscillations can arise around this place inasmuch as the screw thread itself must have a certain play and therefore cannot offer a suicient resistance to the vibratingforces. v

According to the present invention a connection between the propeller blade and the hub body which is free of all vibrationalv stresses, is obtained by forcing the blade shaft and the hub body against one another in at least two places arranged in series one behind the other in the direction of the centrifugal action, the` parts being forced against each other directly or indirectly,

suitable transmission members being inserted between them. Besides avoiding vibrations of the blade shaft in the hub body the novel arran ment furtherinvolves the 'advantage that t e distance along which the hub sleeve overlaps the pro eller shaft can be made shorter than was itherto 4admissible and in consequence thereof the weight of the propeller is reduced. The centrifugal forces canbe taken up in any suitable manner, for

instance by means of a screw :thread or a kind of bayonet joint. Preferably the means for taln'ng up the centrifugal forces are arranged intermediate between the two places in which the parts are pressed against each other.

In a preferred form of m invention I causethe blade shaft screwe linto or onto a hub sleeve and provided with a conical end face-to be lpressed in one place against the hub sleeve by a structural part provided with a corresponding conical face and connected wlth the sleeve, while in another place .the end of the hub sleeve is pressed against the shaft. In order to provide for an adjusting of the pitch of the propeller when the shaft is connected with the hub by screwing, a separate member pressing tl. i end of the shaft against the hub sleeve can be arranged on this sleeve for displacement, for instance by screwing. If the end of the bfade shaft and the hub sleeve are pressed against each other indirectly. the member to be forced in between the two parts is preferably made resilient in radial direction in order to securea proper pressing action. can press the end of the hub sleeve against the blade shaft by means of a pressure rin placed on the slightly conical, radially yiel ing end of the hub sleeve. Both, the member which causes the end of the blade shaft to be pressed against the hub sleeve and the pressure ring pressing the end of the sleeve against the shaft are preferably held in position by a common locking means in order to prevent loosening of the parts.

ln the drawings aixed to this specification and forming part thereof three forms of a propeller embodying my invention are illustrated diagrammatically by way of example, In the drawings Fig. 1 is an axial section of the hub, with one of the sleeves and the end of a blade shaft mounted'therein, one half of the propeller shaft being shown in elevation. p

Fig. 2 illustrates in a similar manner one half of a hub sleeve and propeller shaft fastened together in a different way.

Fig. 3 is an axial sectlon of part of a hub sleeve and propeller shaft with means for pressingsame together in a resilient manner.

Referring first to Fig. 1, 1 is the propeller shaft'and 2 is the hub locked thereon by means of a locking member 21. 6 is 011el of the two sleeves forming part of the Ahub 2, and 5 is the externally screw threaded end of the hollow shaft of a blade fixed in the sleevev 6. The end of the hollow shaft is made resilient by radial slots 14 and a conical surface 3 is surface 3 of the -blade ,100 internally screw threaded,

- provided near the free edge of the shaft. A

ward direction. The pressure exerted on the end of the shaft by the ring causes this end to be forced a anst the inner threaded wall of sleeve 6. ing 8 can be dis laced by screwing from the outside by intro ucing a suitable tool through an aperture 10 provided in the sleeve 6, this tool entering suitable holes 13 arranfged in the ring 8.

The outer end o silient by means of radial slots 11 and is provided with external screw threads. The outer surface of the free end of the sleeve has conical form and a., ressure ring 12 screwed down upon the s eeve and having an inner conical surface 7 will press the end of the sleeve ainst the outer threaded surface of the bla e shaft 5. l

The shaft and sleeve are thus pressed against each other in 'two places arranged 'one behind the other in the direction of the centrifu al action.

In o er to prevent the loosening of the parts pressed together, Aa ledge 15 is mount'- in position by extending into a cavity 18 formed in the sleeve, one ofits ends projecting from below into the locling nut 21 screwed intol the hub and locked against unscrewing. In this manner a loosening of the pressure rings 12 and 8 is avoided.

In the modification illustrated in Fig. 2 the end of blade shaft 5 and sleeve 6 are pressed aglainst each other indirectly b means of t e pressure ring 8 provided wit holes 13 and radial slots 22, this ring having an inner conical surface 9 which "isforced by screwin a ainst the outer conical surface 3 of the b a e shaft.

In the modification illustrated in Fig. 3, the pressure ring 8 has a smooth outer surface and is forced with its conical inner sur` face 9 a'gainst the conical outer surface 3 tweenI the bottom of the sleeve and the pressleeve 6 is also made reof the'blade shaft b centrifugal forces actnecear to lirst-disengage the ring 8" from the sha t and to therea er appl it again. In this case the pressing action o ring 8" is indtpendent from the postion of the blade sha Obviously in all the cases shown and described the position of the parts might as e well be reversed, the hollow 4shaft of the blade being mounted on the outer surface of the sleeve.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilledin the art. v

I claim 4 y .1. Propeller comprising a hub, a blade mounted on this hu the contiguous ends of said parts being formed with a conical sarface and yieldin under pressure and conical means displace le by screwing relatively to said parts for pressing them together by the said conical ends.

2. Propeller comprising a hub, a sleeve Afixed to said hub, the hollow shaft `of a blade mounted in contactwith said sleeve and a wedge-like ring inserted between sai arts, said ring being displaceable in axial siraction.

3. Propeller comprising a hub, a sleeve fixed to said hub, the hollow shaft of a blade mounted in contact with said sleeve, and a radially yielding wedge-like ring inserted between said arts, sai ring being displaceable in axial 'rection.

4. Propeller comprising a hub, a blade mounted on this hub, means for pressing said blade and hub together in two disposed one behind the other in the tion of centrifugal action and a ledge mounted on the outer wall of one of said arts so as to lock said parts against axial i lacement.

testimony whereof I ax my signature.

places y direc- 

